Declare Python 3.15 support

It's now voting in the -next job template.

Also move threading tests to the current upper version.

Change-Id: I3f24661d7c425d625a44da785cd321b972cfcf61
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>

.zuul.yaml

@@ -12,17 +12,17 @@
     check:
       jobs:
         - neutron-ovs-tempest-with-oslo-master
-        - oslo-service-tox-py313-threading
+        - oslo-service-tox-py314-threading
     gate:
       jobs:
-        - oslo-service-tox-py313-threading
+        - oslo-service-tox-py314-threading
 
 - job:
-    name: oslo-service-tox-py313-threading
-    parent: openstack-tox-py313
+    name: oslo-service-tox-py314-threading
+    parent: openstack-tox-py314
     description: |
       Run oslo.service threading backend functional regression tests with
       eventlet monkey-patching disabled. This validates spawn-based
       multiprocessing remains safe while native threads are active.
     vars:
-      tox_envlist: py313-threading
+      tox_envlist: py314-threading

pyproject.toml

@@ -23,6 +23,7 @@ classifiers = [
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
     "Programming Language :: Python :: 3.14",
+    "Programming Language :: Python :: 3.15",
     "Programming Language :: Python :: 3 :: Only",
     "Programming Language :: Python :: Implementation :: CPython",
 ]

tox.ini

@@ -12,9 +12,9 @@ commands =
   find . -type f -name "*.py[co]" -delete
   stestr run --slowest {posargs}
 
-[testenv:py313-threading]
+[testenv:py314-threading]
 description = Threading backend functional tests with eventlet monkey-patching disabled
-basepython = python3.13
+basepython = python3.14
 setenv =
   OSLO_SERVICE_SKIP_EVENTLET=1
 deps =